[etcd/client/v3/lease.go] nextKeepAlive variable - make divide by 3 (now hardcoded) configurable

[angroszew]

What would you like to be added?

Now, divider in nextKeepAlive := time.Now().Add((time.Duration(karesp.TTL) * time.Second) / 3.0) is hardcoded as 3.0
Is it possible to make it configurable?

Why is this needed?

We are using etcd package in a client to etcd db. We need to have possibility to configure when nextKeepAlive is sent by configuring nextKeepAlive divider (now it is hardcoded to 3.0). We have TTL set to 15secs (for example) and we need to cover edge scenarios when there is a need to refresh lease more often than every 5 seconds.